MANETs (Mobile Ad hoc Network) is a kind of network in which all the nodes are connected via wireless link. There is no fixed infrastructure because of which any node can join or leave the network at any point time. There is no central monitoring system. All the nodes are working as host as well as client at the same time. This makes the network vulnerable to different kind of attacks. Standard routing protocols are also not that secured to protect the network from all probable attacks. Attacker may attack the network and disrupt the network services abruptly. Some of the common attacks in MANETs are Rushing attack, Black hole attack, Sybil attack, Neighbor attack and Jellyfish attack etc. In this paper we are trying to accumulate different probabilities of getting rushing attack in MANETs. And also discuss about different counter measures to prevent as well as to detect rushing attack. Keywords:Rushing attack, MANETs, Security, Denial of Service (DoS), Security threats